The present invention relates to an operating apparatus for a switching device, for example, a small-capacity vacuum circuit breaker.
A conventional operating apparatus for a small-capacity vacuum circuit breaker has a configuration as shown in FIGS. 1 and 2.
As shown in FIG. 1, a vacuum valve 53 is supported by the upper support 52 of a switchboard 51 provided on a truck. An operating rod 54 for operating the movable contact of the vacuum valve is coupled with an operating apparatus 57 provided in the switchboard 51 via an insulating rod 55 and a wiper spring 56 supported by a main shaft 69.
As shown in FIG. 2, the operating apparatus 57 stores the force of a motor 58 in springs (a closing spring 59 and an opening spring 60). Tripping catches (a closing catch 61 and a tripping catch 62), the operating apparatus 57 releases the stored energy and is coupled with the outside world via the wiper spring 56.
While in such an operating apparatus 57, energy is usually stored by the motor 58, it may be stored by engaging a hand lever (not shown) with the output shaft of the motor 58. Although the catches 61, 62 are normally released by the electromagnetic force of coils 65, 66 via paddles (a closing paddle 63 and a tripping paddle 64), they may be released by pressing buttons (a closing button 67 and an opening button 68) with a hand.
In such a conventional operating apparatus for a vacuum circuit breaker, however, the operating apparatus is composed of a large number of component parts and is therefore large in scale. For this reason, it is required to provide an operating apparatus which is simple in mechanism and capable of operating stably by obtaining a large contact load.
Accordingly, it is an object of the present invention to provide an operating apparatus for a switching device which produces a large contact load with a simple mechanism and operates stably over a long stroke.
According to an aspect of the present invention, there is provided an operating apparatus for operating a switching device having a movable contact and a fixed contact so provided that they can contact each other and separate from each other, comprising: an operating rod which is fixed to the movable contact and is held such that the rod can move in a direction in which the movable contact makes into contact with or is separated from the fixed contact; a movable member which is connected to the operating rod such that the member can move relatively to the rod and the relative movement to the operating rod is limited to a specific movable range; a fixed member for holding the movable member such that the movable member can move; a first elastic member for acting the operating rod with respect to the movable member in the direction in which the movable contact is pressed against the fixed contact; a permanent magnet for attracting the movable member with respect to the fixed member; a closing magnetic circuit so constructed that, when the movable contact is in contact with the fixed contact and the switching device is closed, N and S poles of the permanent magnet attract the fixed member in the direction in which the movable contact is pressed against the fixed contact; an opening magnetic circuit so constructed that, when the movable contact is apart from the fixed contact and the switching device is open, at least one of the N and S poles of the permanent magnet attract the fixed member in the direction in which the movable contact is separated from the fixed contact; and an operating electromagnet for increasing and decreasing the magnetism in the closing magnetic circuit and the opening magnetic circuit.
The operating apparatus may further comprise a second elastic member for acting the movable member with respect to the fixed member in the direction in which the movable contact is separated from the fixed contact.
The operating apparatus may further comprise a third elastic member for acting the movable member with respect to the fixed member in the direction in which the movable contact is pressed against the fixed contact in an open position where the movable contact is apart from the fixed contact.
In the operating apparatus, if a reaction force that the operating rod exerts on the movable member by the action of the first elastic member is Fk1, a reaction force that the fixed member exerts on the movable member by the action of the second elastic member is Fk2, and the permanent-magnet-generated attracting force that the fixed member acts on the movable member is Fm, setting may be done in the movable range of the movable member such that the changing characteristic of Fk, or Fk1+Fk2, is almost equal to the changing characteristic of Fm.
In the operating apparatus, if a reaction force that the operating rod exerts on the movable member by the action of the first elastic member is Fk1, a reaction force that the fixed member exerts on the movable member by the action of the second elastic member is Fk2, a reaction force that the fixed member exerts on the movable member by the action of the third elastic member is Fk3, and the permanent-magnet-generated attracting force that the fixed member acts on the movable member is Fm, setting may be done in the movable range of the movable member such that the changing characteristic of Fk, or Fk1+Fk2+Fk3, is almost equal to the changing characteristic of Fm.
In the operating apparatus, setting may be done such that, when the movable contact is pressed against the fixed contact and the switching device is closed, an expression Fk less than Fm holds, and when the switching device is open, an expression Fk greater than Fm holds.
In the operating apparatus, the operating electromagnet may be composed of a closing operating electromagnet located in the closing magnetic circuit and an opening operating electromagnet located in the opening magnetic circuit.
The operating apparatus may further comprise: a peep door which is provided in part of the opening magnetic circuit or the closing magnetic circuit, can be opened and closed freely, and allows the N and S magnetic poles of the permanent magnet to be peeped at; and a magnetic force short member which has such a size as can be inserted through the peed door and pressed against the N and S poles and is made of a permeability material.
In the operating apparatus, the peed door may also serve as the magnetic force short member.
In the operating apparatus, the opening magnetic circuit may be so constructed that, when the movable contact is apart from the fixed contact and the switching device is open, the N and S poles of the permanent magnet attract the fixed member in the direction in which the movable contact is separated from the fixed contact.
The operating apparatus may further comprise: a second elastic member for acting the movable member with respect to the fixed member in the direction in which the movable contact is separated from the fixed contact; and a third elastic member for acting the movable member with respect to the fixed member in the direction in which the movable contact is pressed against the fixed contact.
In the operating apparatus, if the reaction force that the operating rod exerts on the movable member by the action of the first elastic member is Fk1, the reaction force that the fixed member exerts on the movable member by the action of the second elastic member is Fk2, the reaction force that the fixed member exerts on the movable member by the action of the third elastic member is Fk3, and the permanent-magnet-generated attracting force that the fixed member acts on the movable member is Fm, setting may be done in the movable range of the movable member such that the changing characteristic of Fk, or Fk1+Fk2+Fk3, is almost equal to the changing characteristic of Fm.
In the operating apparatus, one of the N and S poles of the permanent magnet may be a part to increase a force of attraction or a force of repulsion so as to accelerate the movable member in a direction of motion in the movable range of the movable member.
In the operating apparatus, setting may be done such that, when the movable contact is pressed against the fixed contact and the switching device is closed, an expression Fk less than Fm holds, and when the switching device is open, an expression Fk greater than Fm holds.
In the operating apparatus, attracting surfaces of the N and S poles of the closing magnetic circuit and the opening magnetic circuit may be placed in staggered fashion in the direction in which the movable member moves.
In the operating apparatus, a distance by which attracting surfaces of the N and S poles are staggered may be longer than or almost equal to a stroke in which the movable member moves.
In the operating apparatus, the closing magnetic circuit and/or the opening magnetic circuit may be so constructed that areas of attracting surfaces of the N and S poles are nearly equal.
In the operating apparatus, a density of magnetic flux created by the permanent magnet may be designed to come closer to a magnetic saturation staring point of a material at attracting surfaces of the closing magnetic circuit and/or the opening magnetic circuit in a state where the attracting surfaces has approached the fixed member.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.